1. Field of the Invention
The present invention relates to a display substrate for a liquid crystal display (LCD) device, and a display panel having the display substrate.
2. Discussion of the Background
An LCD device typically uses optical anisotropy and light polarization to display an image. By driving a voltage applied to a liquid crystal layer including liquid crystal molecules that have long and thin molecular structures, the alignment of the liquid crystal is molecules in the liquid crystal layer may be changed and the light transmittance of the liquid crystal layer may be controlled. The LCD device displays an image by controlling the quantity of polarized light using optical anisotropy of the liquid crystal molecules.
A display panel of the LCD device is formed by interposing the liquid crystal layer between two substrates. In order to display an image on the display device, the alignment of liquid crystal molecules in the liquid crystal layer should be uniformly controlled. For example, in a vertical alignment (VA) mode for aligning the liquid crystal molecules, a vertical electric field is applied to the liquid crystal layer. In an in-plane switching (IPS) mode for aligning the liquid crystal molecules, a horizontal electric field is applied to the liquid crystal layer.
In the VA mode, a domain, in which the liquid crystal molecules are aligned, is divided into a plurality of regions to increase a viewing angle. The VA mode for increasing the viewing angle includes a patterned vertical alignment (PVA) mode for patterning a common electrode disposed on an upper substrate of the display panel. A multi-domain vertical alignment (MVA) mode for forming a protrusion on the upper substrate of the display panel has been developed. A photoalignment VA mode for defining multiple domains by controlling a pretilt angle on the photoalignment film has also been developed.
The photoalignment VA mode does not pattern a pixel electrode of a lower substrate and a common electrode of an upper substrate. Thus, light transmittance and aperture ratio in the photoalignment VA mode may be better than those in the PVA mode. The photoalignment VA mode may also have better display properties than the MVA mode having the protrusion on the upper substrate. However, a viewing angle of the photoalignment VA mode may be narrower than that of the IPS mode using the horizontal electric field.